package cn.edu.scau.cmi.lintianwei.hibernate.factory;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

public class HibernateSessionFactory {

	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
	private static org.hibernate.SessionFactory sessionFactory;

	private static Configuration configuration = new Configuration().configure();
	private static ServiceRegistry serviceRegistry;

	static {
		try {
			serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
					.buildServiceRegistry();
			sessionFactory = configuration.buildSessionFactory(serviceRegistry);
		} catch (Exception e) {
			System.err.println("Error Creating SessionFactory ");
			e.printStackTrace();
		}
	}

	private HibernateSessionFactory() {

	}

	/**
	 * Returns the ThreadLocal Session instance. Lazy initialize the
	 * <code>SessionFactory</code> if needed.
	 *
	 * @return Session
	 * @throws HibernateException
	 */
	public static Session getSession() throws HibernateException {
		Session session = (Session) threadLocal.get();

		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			session = (sessionFactory != null) ? sessionFactory.openSession() : null;
			threadLocal.set(session);
		}

		return session;
	}

	/**
	 * Rebuild hibernate session factory
	 *
	 */
	public static void rebuildSessionFactory() {
		try {
			configuration.configure();
			serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties())
					.buildServiceRegistry();
			sessionFactory = configuration.buildSessionFactory(serviceRegistry);
		} catch (Exception e) {
			System.err.println("Error Creating SessionFactory ");
			e.printStackTrace();
		}
	}

	/**
	 * Close the single hibernate session instance.
	 *
	 * @throws HibernateException
	 */
	public static void closeSession() throws HibernateException {
		Session session = (Session) threadLocal.get();
		threadLocal.set(null);

		if (session != null) {
			session.close();
		}
	}

	/**
	 * return session factory
	 *
	 */
	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	/**
	 * return hibernate configuration
	 *
	 */
	public static Configuration getConfiguration() {
		return configuration;
	}

}